Safety has taken a back seat to cost-cutting at most of the nation's nuclear power plants, sparking fears that America could be facing its own Fukushima disaster.

An investigation by the Associated Press has revealed federal regulators are repeatedly weakening - or simply failing to impose - strict rules.

Officials at the U.S. Nuclear Regulatory Commission have frequently decided that original regulations were too strict, arguing that safety margins could be eased without peril.

Failed cables. Cracked concrete, corroded metals and rusty underground pipes — all of these and thousands of other problems linked to aging were uncovered in the AP's year-long investigation.

Yet despite the growing problems linked to aging, not a single official body in government or industry has studied the overall frequency and potential impact on safety of such breakdowns in recent years.